Fabric pilling is a serious problem for the textile and the apparel industry. Pilling is a fabric surface fault in which “pills” of entangled fibers protrude from the fabric surface. They give a bad appearance and can sometimes deteriorate the properties of the fabric. The development of surface hairiness may be an important factor in degrading the quality of certain fabrics and papers.
Due to the importance of the subject, the process of pill formation in fabrics by rubbing action has been thoroughly investigated. Consequently, there are many different test methods that have been developed to determine the resistance of fabrics to pilling. The measurement of pills is performed in two stages. The first entails the formation of pills by means of a laboratory test apparatus—all pill-formation apparatus is based on either tumbling or abrading the test specimen. The second stage is the evaluation of the pilling degree by subjective methods. This is done by comparing the pilled samples with a set of standard photographs or holograms that portray samples of fabrics with various degrees of pilling severity. Other methods involve the manual counting and weighing of the pills.
The pilling standards that are used to grade the samples of tested fabric are on the following scale: 5=no pills; 4=slight pilling; 3=moderate pilling; 2=severe pilling; 1=very severe pilling
The development of an objective method of pill, fuzziness, snag and overall general grading is a valuable contribution to the field of fabric testing.
Methods and apparatus for inspecting fabric surfaces are quite common. Lane in U.S. Pat. No. 5,774,177 describes an apparatus for automatically detecting defects within the field of view of a video camera. The image received is then processed by a blob analysis to identify the defects. Vachtsevanos et al, in U.S. Pat. No. 5,936,665 describes an automated apparatus for counting “pills” in textile fabrics. This patent utilizes a CCD camera to capture an area of the fabric surface. The image of the surface is then processed for counting the “pills” and the data is fuzzified to determine the membership of the data in one or more of a plurality of fabric classes. In these examples and other, an area of the tested fabric is illuminated, captured by electro-optical apparatus and the data is processed to yield the characteristic data of the fabric surface.